Light‐Driven Cobalt Size Modulation on Boron Nitride Enables On‐Demand Reactive Oxygen Species Programming

ABSTRACT The precise modulation of reactive oxygen species (ROS) in Fenton‐like systems holds transformative potential for environmental remediation and oxidative synthesis, yet remains constrained by challenges in tailoring metal catalyst structures across atomic‐to‐nano scales. Herein, guided by theoretical predictions, we devise a light‐assisted synthetic strategy enabling quasi‐continuous regulation of cobalt configurations from single atoms (Co SA ) to nanoparticles (Co NP‐8 ) on porous boron nitride ( p‐ BN). This structural engineering triggers a paradigm shift in ROS mechanisms within peroxymonosulfate (PMS) activation, which achieves a controlled transition from nonradical (90%) to radical (87%) pathways, surpassing most reported systems in both regulation range and accuracy. Leveraging distinct ROS oxidation features, the p ‐BN/Co SA ‐PMS system synergizes with membrane filtration to enable selective aromatic aldehyde synthesis, while p ‐BN/Co NP‐8 ‐PMS facilitates rapid organic pollutant degradation, with both systems maintaining exceptional reaction efficiencies and water fluxes (6000 L m −2 h −1 bar −1 ). This reported design framework for transition metal catalysts establishes a versatile platform for dynamic ROS manipulation, advancing applications spanning green chemistry to environmental engineering.